This invention relates generally to air conditioning systems and, more particularly, to the application of a thermo-charger apparatus to a multiple fan coil air conditioning system.
The use of multiple indoor coils in combination with a single outdoor coil in a so-called multiplex system is becoming more popular where it is desirable to control the environment in individual rooms such as in residential and light commercial applications. It is common in such systems to have only a portion of the fan coils in active operation at any particular time. When this occurs, the smaller active indoor coil(s) tends to be overpowered by the relatively larger outdoor coil which is necessarily large enough for use with the entire indoor coil array. For example, in a typical unit with three indoor coils, there will often be times when only one of those coils is in active operation. If the system is being used in the heating mode, there will be insufficient condensing surface to maintain a balanced condition. As a result, the compressor discharge pressure will tend to increase until it reaches a predetermined threshold point, at which time a safety switch will turn the system off.
If the single indoor coil is being used in the cooling mode, the unbalanced condition will tend to increase the level of superheating in the evaporator coil. This, in turn, will tend to decrease, and eventually cause the loss of, suction to the compressor. In addition, the operation at such higher superheat conditions will be less efficient.
One approach to solving the problem of system imbalance as described hereinabove is that of providing a bleed-off valve between the high and low pressure sides of the system. The temperature at the low pressure side is sensed, and when it reaches a predetermined threshold level, the bleed-off valve is opened to allow a portion of the liquid refrigerant to flash over to the low pressure side where it returns to the compressor without first passing through the indoor coil. In this way, system balance may be maintained. However, it will be recognized that in such a system, the single active indoor coil does not operate as efficiently as it would otherwise operate under normally balanced conditions.
It is therefore an object of the present invention to provide for a multiplex air conditioning system with improved operational characteristics.
Another object of the present invention is the provision in a multiplex air conditioning system for maintaining a thermodynamically balanced system during periods when only a portion of the fan coil array is in active operation.
Yet another object of the present invention is the provision in a multiplex air conditioning system for improved efficiencies when operating with only a portion of the indoor coils in active operation.
Yet another object of the present invention is the provision for a multiplex air conditioning system which is economical to manufacture and useful in operation.
These objects and other features and advantages become more readily apparent upon reference to the following description when taken in conjunction with the appended drawings.